They are devoted foster parents with an unblemished record of caring for almost 30 vulnerable children. But Vincent and Pauline Matherick will this week have their latest foster son taken away because they have refused to sign new sexual equality regulations.

To do so, they claim, would force them to promote homosexuality and go against their Christian faith.

The 11-year-old boy, who has been in their care for two years, will be placed in a council hostel this week and the Mathericks will no longer be given children to look after.

Earlier this year, Somerset County Council's social services department asked them to sign a contract to implement Labour's new Sexual Orientation Regulations.

Officials told the couple that under the regulations they would be required to discuss same-sex relationships with children as young as 11 and tell them that gay partnerships were just as acceptable as heterosexual marriages. They could also be required to take teenagers to gay association meetings.

When the Mathericks objected, they were told they would be taken off the register of foster parents.

The Mathericks have decided to resign rather than face the humiliation of being expelled.

Mr Matherick, a 65-year-old retired travel agent and a primary school governor, said: "I simply could not agree to do it because it is against my central beliefs.

"We have never discriminated against anybody but I cannot preach the benefits of homosexuality when I believe it is against the word of God."

The Mathericks' case comes at a time when there is a chronic shortage of foster parents, who work on a voluntary basis.

The "haves" are generally those in stable marriages. The "have-nots" are generally those who live outside of marriage, especially with children.

So vast is the difference, one is tempted to replace the traditional notion of social class with the more descriptive term marriage class.

Marriage now divides the population in much the same way social class once did.

Indeed, it may do so more profoundly. Neither education nor occupation so clearly discriminates between those at the two ends of the economic spectrum as marital status does. Those with higher levels of education, income, and occupational stability are more likely to be married and vice versa.

The poor or precarious are more likely to be single and vice versa.

- from Steven L. Nock, "Illustrations of Family Scholarship: Introduction to the Special Issue", Social Science Research 35 (June 2006).